pkgspecial.go

     1  // Copyright 2023 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package objabi
     6  
     7  import "sync"
     8  
     9  // PkgSpecial indicates special build properties of a given runtime-related
    10  // package.
    11  type PkgSpecial struct {
    12  	// Runtime indicates that this package is "runtime" or imported by
    13  	// "runtime". This has several effects (which maybe should be split out):
    14  	//
    15  	// - Implicit allocation is disallowed.
    16  	//
    17  	// - Various runtime pragmas are enabled.
    18  	//
    19  	// - Optimizations are always enabled.
    20  	//
    21  	// - Checkptr is always disabled.
    22  	//
    23  	// This should be set for runtime and all packages it imports, and may be
    24  	// set for additional packages.
    25  	Runtime bool
    26  
    27  	// NoInstrument indicates this package should not receive sanitizer
    28  	// instrumentation. In many of these, instrumentation could cause infinite
    29  	// recursion. This is all runtime packages, plus those that support the
    30  	// sanitizers.
    31  	NoInstrument bool
    32  
    33  	// NoRaceFunc indicates functions in this package should not get
    34  	// racefuncenter/racefuncexit instrumentation Memory accesses in these
    35  	// packages are either uninteresting or will cause false positives.
    36  	NoRaceFunc bool
    37  
    38  	// AllowAsmABI indicates that assembly in this package is allowed to use ABI
    39  	// selectors in symbol names. Generally this is needed for packages that
    40  	// interact closely with the runtime package or have performance-critical
    41  	// assembly.
    42  	AllowAsmABI bool
    43  }
    44  
    45  var runtimePkgs = []string{
    46  	// TODO(panjf2000): consider syncing the list inside the
    47  	// 	isAsyncSafePoint in preempt.go based on this list?
    48  
    49  	"runtime",
    50  
    51  	"internal/runtime/atomic",
    52  	"internal/runtime/exithook",
    53  	"internal/runtime/maps",
    54  	"internal/runtime/math",
    55  	"internal/runtime/sys",
    56  	"internal/runtime/syscall",
    57  
    58  	"internal/abi",
    59  	"internal/bytealg",
    60  	"internal/byteorder",
    61  	"internal/chacha8rand",
    62  	"internal/coverage/rtcov",
    63  	"internal/cpu",
    64  	"internal/goarch",
    65  	"internal/godebugs",
    66  	"internal/goexperiment",
    67  	"internal/goos",
    68  	"internal/profilerecord",
    69  	"internal/stringslite",
    70  }
    71  
    72  // extraNoInstrumentPkgs is the set of packages in addition to runtimePkgs that
    73  // should have NoInstrument set.
    74  var extraNoInstrumentPkgs = []string{
    75  	"runtime/race",
    76  	"runtime/msan",
    77  	"runtime/asan",
    78  	// We omit bytealg even though it's imported by runtime because it also
    79  	// backs a lot of package bytes. Currently we don't have a way to omit race
    80  	// instrumentation when used from the runtime while keeping race
    81  	// instrumentation when used from user code. Somehow this doesn't seem to
    82  	// cause problems, though we may be skating on thin ice. See #61204.
    83  	"-internal/bytealg",
    84  }
    85  
    86  var noRaceFuncPkgs = []string{"sync", "sync/atomic", "internal/sync", "internal/runtime/atomic"}
    87  
    88  var allowAsmABIPkgs = []string{
    89  	"runtime",
    90  	"reflect",
    91  	"syscall",
    92  	"internal/bytealg",
    93  	"internal/chacha8rand",
    94  	"internal/runtime/syscall",
    95  	"runtime/internal/startlinetest",
    96  }
    97  
    98  // LookupPkgSpecial returns special build properties for the given package path.
    99  func LookupPkgSpecial(pkgPath string) PkgSpecial {
   100  	return pkgSpecialsOnce()[pkgPath]
   101  }
   102  
   103  var pkgSpecialsOnce = sync.OnceValue(func() map[string]PkgSpecial {
   104  	// Construct pkgSpecials from various package lists. This lets us use
   105  	// more flexible logic, while keeping the final map simple, and avoids
   106  	// the init-time cost of a map.
   107  	pkgSpecials := make(map[string]PkgSpecial)
   108  	set := func(elt string, f func(*PkgSpecial)) {
   109  		s := pkgSpecials[elt]
   110  		f(&s)
   111  		pkgSpecials[elt] = s
   112  	}
   113  	for _, pkg := range runtimePkgs {
   114  		set(pkg, func(ps *PkgSpecial) { ps.Runtime = true; ps.NoInstrument = true })
   115  	}
   116  	for _, pkg := range extraNoInstrumentPkgs {
   117  		if pkg[0] == '-' {
   118  			set(pkg[1:], func(ps *PkgSpecial) { ps.NoInstrument = false })
   119  		} else {
   120  			set(pkg, func(ps *PkgSpecial) { ps.NoInstrument = true })
   121  		}
   122  	}
   123  	for _, pkg := range noRaceFuncPkgs {
   124  		set(pkg, func(ps *PkgSpecial) { ps.NoRaceFunc = true })
   125  	}
   126  	for _, pkg := range allowAsmABIPkgs {
   127  		set(pkg, func(ps *PkgSpecial) { ps.AllowAsmABI = true })
   128  	}
   129  	return pkgSpecials
   130  })
   131
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